1. Field of Invention
This invention relates to window shades, collapsible partitions, folding screens, and the like.
2. Prior Art
Among the product categories within the window coverings industry are various types of curtains; Roman shades or blinds; Venetian blinds; pleated shades; roll-up or roller shades; vertical blinds; and others. In terms of functional typology, this list can account for almost all the products on the market at present and at any time in the past. This list of categories has remained unchanged for 50 years or more. The most recent category is vertical blinds, which were invented in the 1890s, but were not commercially popular until the 1940s. The rest of the categories have existed for hundreds of years.
Based on a review of prior art, the vast majority of improvements to window coverings have been detail-oriented rather than aesthetically based. Toti et al. (U.S. Pat. No. 2,567,256) disclose a Venetian blind with parallel undulating slats to provide a drapery like appearance. Toti recognizes that “the great objection to the use of Venetian blinds in artistic homes and buildings is that they contribute a barred window effect which is jail-like in its mechanical precision” which is overcome by Toti's undulating, rather than rigid, slats. Recent improvements in Venetian blinds have changed their overall visual effect very little. The same is true of the pleated shade and its most recent incarnation called the “cellular shade”, which is essentially a pair of parallel-pleated webs of material glued together at every second pleat as exemplified by U.S. Pat. No. 5,104,469 and by U.S. Pat. No. 5,313,998, both by Colson, disclosing an expandable window covering in which a non-pleated fabric is attached to a pleated panel.
In addition, some other categories of window coverings have their own disadvantages. Curtains and Roman-type shades made of textiles are generally labor-intensive and thus costly to produce. Roll-up shades usually add little aesthetic effect to their surrounding environment, except for that contributed by the textile from which it is made. Vertical blinds, Venetian blinds, and pleated shades cannot be better described than by Toti as cited above.
Origami
Origami, the art of paper folding, has been practiced perhaps for as many centuries as paper has existed. Its basic tenets are that a square piece of paper is folded (typically not cut, glued, or otherwise transformed) into abstract representations of animals, objects, or geometrical shapes. Origami makes use of a large body of standard “base” fold-patterns and various styles of folding such as box pleating, modular origami, pictorial origami, and others. Origami has been practiced almost exclusively without lucrative or utilitarian ends.
Models exist for such things as slippers, dishes, cups, lampshades (traditional Chinese lanterns and Scandinavian designs of the 1960s), and folded maps (as in U.S. Pat. No. 4,502,711, “Sheet folding method and product”, Muth, 1985, which is an improvement on an origami map fold). Patents have been issued for purely decorative objects that exhibit origami folds: U.S. Pat. No. 2,164,966 (Tutein, 1939) discloses a “pleated material and method” that is essentially a tessellation of folds, and U.S. Pat. No. 2,922,239 (“Decorative ornament”, Glynn, 1960) is an improvement on an origami model called a flexagon which was first folded by Arthur Stone in the UK in 1939 (Kenneway, E., Complete Origami, New York, St. Martin's Press, 1987, p. 57).
Origami-type folds have been used in materials other than paper and for uses other than decorative. An example is Nojima's published application No. WO 01/081821 of 2001 entitled “Structure with folding lines, folding line forming mold, and folding line forming method”, which suggests the formation of collapsible objects in flexible plastic, such as PET bottles, making use of patterns of folds known to the field of origami.
Furthermore, structures based on origami folds, or based on models folded in paper to simulate large-scale structures, take advantage of the fact that the rigidity or stiffness of a sheet material can be increased by the addition of folds. Examples include GB Patent 1,170,785 (Quarmby, 1966) titled “Foldable building units”, GB Patent 2,119,825 (Singh et al., 1982) titled “Erecting folded-plate structure”, and U.S. Pat. No. 3,939,615 (Sorkin, 1976) titled “Foldable roof construction element”. The rarity of such structures in commerce today might show that they rely on material strength characteristics that go beyond what is possible in a sufficiently large dimension, or that problems associated with cost remain unsolved. Also, such models gain rigidity through folding, but they do not gain stability; their stability is largely dependent on their anchor points on the ground.
Origami Mathematics and Computational Origami
Mathematicians, physicists, and other scientists have interested themselves in origami in recent years. One interest is to represent the folding of paper mathematically, in order to analyze and predict the folding of paper (or other sheet materials) for applications in engineering, chemistry and medicine on a molecular scale, and other sciences. Exemplary articles include:    Cipra, Barry A., “In the Fold: Origami Meets Mathematics”, SIAM News, Vol. 34, No. 8, ff. 1-4.    Hull, Thomas, “Counting Mountain-Valley Assignments for Flat Folds”, Ars Combinatoria, 2002.    Hull, Thomas, “The Combinatorics of Flat Folds: a Survey”, The Proceedings of the Third International Meeting of Origami Science, Mathematics, and Education, A. K. Peters, 2002.
There has been recent interest in a relatively new type of origami called the tessellation, a geometric pattern of concave and convex fold lines, imparted and repeated ad infinitum into a planar sheet. Examples include US Patent application 2005/0113235 by B. Basily and E. Elsayed entitled “Technology for continuous folding of sheet materials” and US Patent application 2002/0094926 by D. Kling titled “Patterning technology for folded sheet structures”, both of which apply to the manufacture of tessellated webs or continuous sheets of material intended for use in structural hollow-core building materials, and US Patent application 2004/0098101 by Z. You and K. Kuribayashi entitled “Deployable Stent” is an origami-based medical implant that unfolds inside the human body. Tessellations of folds or hinges have also been used to design a deployable Fresnel lens for use in a space telescope.
No Prior Combination of Origami and Window Coverings
With reference to all the above cited examples of concentrated study and practical application of origami, as well as countless other examples not referenced herein, a thorough search of relevant prior art has revealed no examples of origami folds being applied to a functional window covering.
In Japan, although paper has long been used to cover shoji screens and sliding doors, it has always been used passively, glued to the rigid frame, despite the Japanese invention of the art of origami. US and foreign Patents for window shades have been observed wherein paper was once a commonly used material, yet the shades were always folded with parallel folds. The very common “pleated window shade” always makes use of parallel pleats, even when its inventor seeks to create some different aesthetic effect on the window. For example, Park's U.S. Pat. No. 451,068 of 1891 entitled “Window Shade” discloses a way in which a typical pleated window shade can be raised on one side, creating an arc across the window so that it is “draped artistically as by a lace curtain or lambrequin”. Another example is U.S. Pat. No. 6,431,245 (Shen, 2002), disclosing a hinged bottom stave which causes the pleated material to form a semicircular bottom edge when raised, once again using the standard parallel pleats.
Still other Patents for pleated window shades reflect alterations of shape imposed by the architectural opening in which they are to be installed: Schnebly's U.S. Pat. No. 4,934,436 (1990) discloses pleated shades and their mechanisms for semicircular and other nonrectangular windows, every example showing parallel pleats. Zimmer's US Patent Application 2006/0289130 is entitled “Window Origami Panels and the Like”, but focuses mainly on fastening the fabric panels to a plurality of fasteners by a number of holes near the edges of the panels; the relevance of origami is only in the visual effect of how the panels are hung.